Fuel injector and common rail fuel injection system

Abstract

The invention discloses an injector and a common rail fuel injection system, and relates to the technical field of diesel engines. The injector comprises: a supercharging part, comprising a supercharging cylinder and a piston; and an injection part, comprising an injector body, a control valve and a needle valve. The control valve comprises a control valve stem and a driving mechanism, and the driving mechanism can drive the control valve stem to move to a first position, so that the control valve stem simultaneously blocks a first on-off port and a second on-off port, conducts the oil path between the control chamber and the oil drain port, and conducts the oil path between the oil inlet and the supercharging oil inlet chamber, thereby causing the needle valve to close the injection port; the driving mechanism can also drive the control valve stem to move to a second position, so that the control valve stem simultaneously opens the first on-off port and the second on-off port, disconnects the oil path between the control chamber and the oil drain port, and disconnects the oil path between the oil inlet and the supercharging oil inlet chamber, thereby causing the needle valve to open the injection port. The injector can provide a higher fuel injection pressure, simplify the setting of the common rail fuel injection system, and reduce costs.

Description

Technical Field

[0001] The invention relates to the technical field of diesel engines, and in particular to a fuel injector and a common rail fuel injection system. Background Art

[0002] For the common rail fuel injection system of a diesel engine, in order to achieve more optimized operation of the diesel engine under all operating conditions, the injectors in the system are required to provide the greatest possible fuel injection pressure to ensure better injection characteristics of the common rail fuel injection system and better diesel engine operating conditions.

[0003] However, higher fuel injection pressure places higher requirements on the common rail fuel injection system. In the prior art, in order to meet the requirements of higher fuel injection pressure, a booster mechanism that cooperates with the injector is usually required in the common rail fuel injection system so that the injector can provide a higher fuel injection pressure, which makes the overall setting of the common rail fuel injection system more complicated and the cost higher.

[0004] Based on this, there is an urgent need for a fuel injector and a common rail fuel injection system to solve the above problems. Summary of the invention

[0005] The object of the present invention is to provide a fuel injector and a common rail fuel injection system, which do not require an additional booster mechanism and can provide a higher fuel injection pressure through the fuel injector itself, thereby simplifying the setting of the common rail fuel injection system and reducing costs.

[0006] To achieve this object, the present invention adopts the following technical solutions:

[0007] A fuel injector comprises a pressure boosting part and a fuel injection part;

[0008] The boosting part includes a boosting cylinder and a piston, wherein the piston is movably disposed in the inner cavity of the boosting cylinder, and two ends of the piston cooperate with two ends of the inner cavity of the boosting cylinder to form a boosting oil inlet cavity and a boosting oil outlet cavity respectively;

[0009] The fuel injection part comprises a fuel injector body, a control valve and a needle valve, the fuel injector body is provided with a fuel inlet, a fuel drain and a fuel injection port, the control valve and the needle valve are sequentially installed in the fuel injector body along the axial direction of the fuel injector body, the two ends of the needle valve cooperate with the inner wall of the fuel injector body to form a control chamber and a fuel injection chamber respectively, the fuel injection chamber forms the fuel injection port on the fuel injector body, the fuel inlet is communicated with the boost fuel inlet chamber, the boost fuel outlet chamber and the control chamber, the boost fuel outlet chamber is communicated with the fuel injection chamber, the control chamber is communicated with the fuel drain, a first on-off port is provided on the oil path connecting the control chamber and the fuel drain, and a second on-off port is provided on the oil path connecting the fuel inlet and the boost fuel inlet chamber;

[0010] The control valve comprises a movable control valve stem and a driving mechanism drivingly connected to the control valve stem, wherein the driving mechanism is configured to drive the control valve stem to move to a first position, so that the control valve stem simultaneously blocks the first on-off port and the second on-off port, thereby causing the needle valve to close the oil injection port;

[0011] The driving mechanism is also configured to drive the control valve stem to move to a second position, so that the control valve stem simultaneously opens the first on-off port and the second on-off port, thereby causing the needle valve to open the oil injection port.

[0012] Optionally, a sealing valve ball is provided at the first end of the control valve stem, and an annular groove is provided on the circumferential outer wall of the second end of the control valve stem;

[0013] When the control valve stem is located at the first position, the sealing valve ball abuts against the first on-off port to block the first on-off port, and the annular groove is communicated with at most one of the oil inlet and the boost oil inlet chamber to block the second on-off port;

[0014] When the control valve stem is located at the second position, the sealing valve ball is lifted away from the first on-off port to open the first on-off port, and the annular groove is simultaneously connected with the oil inlet and the pressurized oil inlet chamber to open the second on-off port.

[0015] Optionally, the control valve is a solenoid valve, and along the direction from the second end of the control valve stem to the first end of the control valve stem, the drive mechanism includes a compression spring, a first return spring, an iron core coil assembly and an armature arranged in sequence;

[0016] The compression spring is arranged between the inner wall of the injector body and the end surface of the second end of the control valve stem, the first return spring is sleeved outside the control valve stem, and the two ends of the first return spring are respectively fixedly connected to the control valve stem and the injector body, the iron core coil assembly is fixedly installed in the injector body, and the armature is fixedly sleeved outside the control valve stem and arranged opposite to the iron core coil assembly;

[0017] When the iron core coil assembly is not energized, the compression spring and the first return spring provide elastic force to keep the control valve stem in the first position; when the iron core coil assembly is energized, the iron core coil assembly drives the control valve stem to move from the first position to the second position through the armature.

[0018] Optionally, along the direction from the second end of the control valve stem to the first end of the control valve stem, the cross-sectional area of ​​the annular groove in a direction perpendicular to the axial direction of the control valve stem gradually increases.

[0019] Optionally, the piston is a T-shaped piston, the large end of the T-shaped piston is the first end of the piston, and the small end of the T-shaped piston is the second end of the piston.

[0020] Optionally, a one-way valve is provided on the oil circuit connecting the oil inlet and the pressurized oil outlet chamber, the inlet of the one-way valve is connected to the oil inlet, and the outlet of the one-way valve is connected to the pressurized oil outlet chamber.

[0021] Optionally, the needle valve includes a needle valve stem, which is configured to move to a third position to block the injection port when the oil pressure in the control chamber is greater than the oil pressure in the injection chamber. The needle valve stem is also configured to move to a fourth position to open the injection port when the oil pressure in the control chamber is less than the oil pressure in the injection chamber.

[0022] Optionally, along the axial direction of the injector body, the control valve stem, the control chamber and the needle valve stem are arranged in sequence.

[0023] Optionally, the boosting part and the fuel injection part are fixedly connected to form an integrated structure.

[0024] The present invention also provides a common rail fuel injection system, which includes the fuel injector as described above. The common rail fuel injection system also includes a common rail pipe, and the outlet of the common rail pipe is connected to the fuel inlet of the fuel injector.

[0025] Beneficial effects of the present invention:

[0026] The present invention provides a fuel injector and a common rail fuel injection system. When a driving mechanism drives a valve stem to move to a first position, the valve stem can block a first on-off port and a second on-off port, thereby disconnecting a control chamber from an oil drain port, so that the control chamber does not leak oil. At the same time, the connection between an oil inlet port and a pressurized oil inlet chamber is disconnected, so that oil does not flow into the pressurized oil inlet chamber, and finally the oil pressure in the control chamber is greater than the oil pressure in the injection chamber, the needle valve closes the injection port, and the fuel injector does not perform an injection operation.

[0027] When the driving mechanism drives the valve stem to move to the second position, the first on-off port and the second on-off port can be opened through the valve stem, so that the control chamber is connected with the oil drain port, the control chamber is drained, and the oil inlet is connected with the boost oil inlet chamber, so that the piston moves and the oil in the boost oil outlet chamber is sent to the injection chamber, and finally the oil pressure in the injection chamber is greater than the oil pressure in the control chamber, the needle valve opens the injection port, and a higher fuel injection pressure is achieved;

[0028] Overall, a higher fuel injection pressure can be provided by the injector itself without the need for an additional boost mechanism, which can simplify the setting of the common rail fuel injection system and reduce costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 is a schematic diagram of the overall structure of a fuel injector provided by an embodiment of the present invention;

[0030] Figure 2 It is a schematic diagram of the local structure of the first on-off port in the fuel injector when the control valve stem provided by the embodiment of the present invention is in the first position;

[0031] Figure 3 It is a partial structural schematic diagram of the first on-off port in the fuel injector when the control valve stem provided by the embodiment of the present invention is in the second position;

[0032] Figure 4 It is a partial structural schematic diagram of the second on-off port in the fuel injector when the control valve stem provided by the embodiment of the present invention is in the first position;

[0033] Figure 5 It is a schematic diagram of the local structure of the second on-off port in the injector when the control valve stem provided by an embodiment of the present invention is in the second position.

[0034] In the figure:

[0035] 1. Pressurizing unit; 11. Pressurizing cylinder; 12. Piston; 13. Pressurizing oil inlet chamber; 14. Pressurizing oil outlet chamber;

[0036] 2. Fuel injection unit; 21. Fuel injector body; 211. Fuel inlet; 212. Fuel drain; 213. Fuel injection port; 214. Control chamber; 215. Fuel injection chamber; 216. First on-off port; 217. Second on-off port; 218. First oil circuit; 219. Second oil circuit; 22. Control valve; 221. Control valve stem; 2211. Sealing valve ball; 2212. Ring groove; 222. Compression spring; 223. First return spring; 224. Core coil assembly; 2241. Core; 2242. Solenoid coil; 225. Armature; 23. Needle valve; 231. Needle valve stem; 232. Second return spring; 24. One-way valve. DETAILED DESCRIPTION

[0037] In order to make the technical problem solved by the present invention, the technical solution adopted and the technical effect achieved more clearly, the technical solution of the present invention is further explained below with reference to the accompanying drawings and through specific implementation methods.

[0038] In the description of the present invention, unless otherwise clearly specified and limited, the terms "connected", "connected", and "fixed" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0039] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0040] In the description of this embodiment, the terms "upper", "lower", "left", "right" and other directions or positional relationships are based on the directions or positional relationships shown in the drawings, and are only for the convenience of description and simplification of operation, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operate in a specific direction, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are only used to distinguish in the description and have no special meaning.

[0041] This embodiment provides a fuel injector, such as Figure 1-Figure 5 As shown, the fuel injector comprises a booster part 1 and a fuel injection part 2. The booster part 1 comprises a booster cylinder 11 and a piston 12, wherein the piston 12 is movably disposed in the inner cavity of the booster cylinder 11, and the two ends of the piston 12 cooperate with the two ends of the inner cavity of the booster cylinder 11 to form a booster oil inlet cavity 13 and a booster oil outlet cavity 14 respectively.

[0042] The fuel injection unit 2 includes a fuel injector body 21, a control valve 22 and a needle valve 23. The fuel injector body 21 is provided with a fuel inlet 211, a fuel drain port 212 and a fuel injection port 213. Along the axial direction of the fuel injector body 21, the control valve 22 and the needle valve 23 are sequentially installed in the fuel injector body 21. The two ends of the needle valve 23 cooperate with the inner wall of the fuel injector body 21 to form a control chamber 214 and a fuel injection chamber 215 respectively. The fuel injection chamber 215 forms a fuel injection port 213 on the fuel injector body 21. The oil inlet 211 is connected to the boost oil inlet chamber 13, the boost oil outlet chamber 14 and the control chamber 214. The boost oil outlet chamber 14 is connected to the oil injection chamber 215. The control chamber 214 is connected to the oil drain port 212. A first on-off port 216 is provided in the oil circuit connecting the control chamber 214 and the oil drain port 212. A second on-off port 217 is provided in the oil circuit connecting the oil inlet 211 and the boost oil inlet chamber 13.

[0043] The control valve 22 includes a movable control valve stem 221 and a driving mechanism connected to the control valve stem 221. The driving mechanism can drive the control valve stem 221 to move to the first position, so that the control valve stem 221 simultaneously blocks the first on-off port 216 and the second on-off port 217, thereby causing the needle valve 23 to close the oil injection port 213. The driving mechanism can also drive the control valve stem 221 to move to the second position, so that the control valve stem 221 simultaneously opens the first on-off port 216 and the second on-off port 217, thereby causing the needle valve 23 to open the oil injection port 213.

[0044] According to the above arrangement, when the driving mechanism drives the valve stem to move to the first position, the valve stem can block the first on-off port 216, thereby disconnecting the control chamber 214 from the oil drain port 212, so that the control chamber 214 does not leak oil; at the same time, the valve stem can block the second on-off port 217, disconnecting the oil inlet port 211 from the boost oil inlet chamber 13, so that oil will not be fed into the boost oil inlet chamber 13, and the piston 12 will not work. At this time, the oil pressure in the control chamber 214 will be greater than the oil pressure in the oil injection chamber 215, so that the needle valve 23 can close the oil injection port 213, and the injector will not perform the oil injection work.

[0045] When the driving mechanism drives the valve stem to move to the second position, the first on-off port 216 can be opened through the valve stem, so that the control chamber 214 is connected to the oil drain port 212, and the control chamber 214 is drained; at the same time, the second on-off port 217 can also be opened through the valve stem, so that the oil inlet 211 is connected to the pressurized oil inlet chamber 13, and then the piston 12 works and sends the oil in the pressurized oil outlet chamber 14 into the injection chamber 215, and pressurizes the injection chamber 215. At this time, the oil pressure in the injection chamber 215 will be greater than the oil pressure in the control chamber 214, so that the needle valve 23 can open the injection port 213 to achieve a higher fuel injection pressure.

[0046] On the whole, a higher fuel injection pressure can be provided by the injector itself, without the need to set up an additional boost mechanism in the common rail fuel system. The cyclical variable injection pattern is also achieved, which can ultimately simplify the setting of the common rail fuel injection system and reduce costs.

[0047] In this embodiment, the booster 1 and the fuel injection part 2 are fixedly connected to form an integrated structure, which makes the overall structure more compact and can save installation space. Further, the booster 1 and the fuel injector body 21 are coaxially arranged to facilitate the arrangement of the oil circuit.

[0048] Next, the specific structure of each component in the injector is introduced.

[0049] Alternatively, if Figure 1As shown, the piston 12 is a T-shaped piston. The large end of the T-shaped piston is the first end of the piston 12, and the small end of the T-shaped piston is the second end of the piston 12, so that a higher oil pressure can be generated in the boost oil outlet chamber 14, and finally the fuel injection pressure can be further increased. Since the specific structure of the T-shaped piston is a prior art, it will not be described here.

[0050] Optionally, a one-way valve 24 is further provided in the oil path connecting the oil inlet 211 and the boost oil outlet chamber 14. The inlet of the one-way valve 24 is connected to the oil inlet 211, and the outlet of the one-way valve 24 is connected to the boost oil outlet chamber 14. Thus, during the process of boosting by the boosting unit 1, the fuel in the boost oil inlet chamber 13 can be prevented from flowing back, thereby ensuring the stability and reliability of the boosting process.

[0051] Optionally, the control valve 22 is a solenoid valve. Along the direction from the second end of the control valve stem 221 to the first end of the control valve stem 221, the driving mechanism includes a compression spring 222, a first return spring 223, an iron core coil assembly 224 and an armature 225 arranged in sequence. The compression spring 222 is arranged between the inner wall of the injector body 21 and the end surface of the second end of the control valve stem 221. The first return spring 223 is sleeved outside the control valve stem 221, and the two ends of the first return spring 223 are respectively fixedly connected to the control valve stem 221 and the injector body 21. The iron core coil assembly 224 is fixedly installed in the injector body 21. The armature 225 is fixedly sleeved outside the control valve stem 221 and arranged opposite to the iron core coil assembly 224. In this embodiment, the iron core coil assembly 224 includes an iron core 2241 and an electromagnetic coil 2242 wound outside the iron core 2241.

[0052] When the core coil assembly 224 is not powered, the electromagnetic coil 2242 does not generate magnetic force, and the compression spring 222 and the first return spring 223 provide elastic force to keep the control valve stem 221 in the first position. On the contrary, when the core coil assembly 224 is powered, the electromagnetic coil 2242 generates magnetic force and attracts the armature 225, thereby driving the control valve stem 221 to move through the armature 225 to overcome the elastic force of the compression spring 222 and the first return spring 223, so that the control valve stem 221 moves from the first position to the second position. It can be further understood that when the core coil assembly 224 is powered off again, the compression spring 222 and the first return spring 223 can reset the control valve stem 221.

[0053] by Figure 1 Taking the direction shown as an example, in this embodiment, the lower end of the control valve stem 221 is the first end of the control valve stem 221, and the upper end of the control valve stem 221 is the second end of the control valve stem 221. The process of the control valve stem 221 moving from the first position to the second position is the process of the control valve stem 221 moving upward.

[0054] Optionally, with regard to the specific structure of the control valve stem 221, a sealing valve ball 2211 is provided at the first end of the control valve stem 221 to control the opening and closing of the first on-off port 216, and an annular groove 2212 is provided on the circumferential outer wall of the second end of the control valve stem 221 to control the opening and closing of the second on-off port 217.

[0055] like Figure 2 and Figure 3 As shown, when the control valve stem 221 is located at the first position, the sealing valve ball 2211 abuts against the first on-off opening 216 to block the first on-off opening 216; when the control valve stem 221 is located at the second position, the sealing valve ball 2211 lifts away from the first on-off opening 216 to open the first on-off opening 216. In this embodiment, the first on-off opening 216 is a tapered opening, and the sealing valve ball 2211 can abut against the conical surface of the tapered opening to block the tapered opening, thereby ensuring reliable sealing.

[0056] Further, when the control valve stem 221 is located in the first position, the annular groove 2212 is connected to at most one of the oil inlet 211 and the boost oil inlet chamber 13 to block the second on-off port 217; when the control valve stem 221 is located in the second position, the annular groove 2212 is connected to the oil inlet 211 and the boost oil inlet chamber 13 at the same time to open the second on-off port 217.

[0057] In this embodiment, Figure 4 and Figure 5 As shown, in the injector body 21, a first oil path 218 is formed between the second on-off port 217 and the oil inlet 211, and a second oil path 219 is formed between the second on-off port 217 and the pressurized oil inlet chamber 13. When the control valve stem 221 is in the first position, the annular groove 2212 is connected to the first oil path 218 and is not connected to the second oil path 219, thereby closing the second on-off port 217. When the control valve stem 221 moves to the second position, the annular groove 2212 is connected to the first oil path 218 and the second oil path 219 at the same time, thereby opening the second on-off port 217.

[0058] In addition, it can be understood from the overall perspective that the control valve 22 is a two-position three-way solenoid valve.

[0059] Furthermore, along the direction from the second end of the control valve stem 221 to the first end of the control valve stem 221, the cross-sectional area of ​​the annular groove 2212 in the direction perpendicular to the axial direction of the control valve stem 221 gradually increases. According to this arrangement, the fuel action area at the lower end of the annular groove 2212 can be larger than the fuel action area at the upper end of the annular groove 2212, so that the elastic force (elastic force provided by the compression spring 222 and the return spring) required to supply the control valve stem 221 to close the first on-off port 216 can be smaller, and thus the electromagnetic force required to open the first on-off port 216 (the electromagnetic force is used to drive the control valve stem 221 to overcome the aforementioned elastic force to move) is also smaller. As a result, the volume of the control valve 22 can be reduced, the installation space can be saved, and a more clever design of the injector is possible, and a higher fuel injection pressure is possible.

[0060] Optionally, the needle valve 23 includes a needle valve stem 231. When the oil pressure in the control chamber 214 is greater than the oil pressure in the oil injection chamber 215, the needle valve stem 231 moves to the third position to block the oil injection port 213. When the oil pressure in the control chamber 214 is less than the oil pressure in the oil injection chamber 215, the needle valve stem 231 moves to the fourth position to open the oil injection port 213. In this embodiment, the movement of the needle valve stem 231 from the third position to the fourth position is a process in which the needle valve stem 231 moves upward.

[0061] Furthermore, a second return spring 232 is sleeved outside the needle valve stem 231, and the two ends of the second return spring 232 are respectively fixedly connected to the needle valve stem 231 and the injector body 21. The second return spring 232 can provide elastic force for the needle valve stem 231, so that the lower end of the needle valve stem 231 is pressed against the injection port 213, thereby blocking the injection port 213.

[0062] More specifically, Figure 1 Taking the example shown, when the sum of the oil pressure in the control chamber 214 and the elastic force of the second return spring 232 is greater than the oil pressure in the injection chamber 215, the needle valve stem 231 will be in the third position, closing the injection port 213; when the sum of the oil pressure in the control chamber 214 and the elastic force of the second return spring 232 is less than the oil pressure in the injection chamber 215, the needle valve stem 231 can move up to the fourth position, thereby opening the injection port 213.

[0063] In this embodiment, the control valve stem 221, the control chamber 214 and the needle valve stem 231 are arranged in sequence along the axial direction of the injector body 21, so that the overall structure is compact and the oil circuit is easy to arrange.

[0064] The present invention also provides a common rail fuel injection system, which includes the fuel injector as described above. Further, the common rail fuel injection system also includes a common rail pipe, the outlet of the common rail pipe is connected to the fuel inlet 211 of the fuel injector to supply fuel to the fuel injector. Since the structure of the common rail pipe is prior art, it will not be described here.

[0065] In summary, the present invention provides a fuel injector and a fuel injection system, which have the following advantages:

[0066] (1) It integrates fuel boosting and fuel injection. Through the combined action of the boosting unit 1, the control valve 22 and the needle valve 23, a higher fuel injection pressure can be obtained, and the injection pattern can be cyclically variable. At the same time, the setting of the common rail fuel injection system is simplified, and the cost is reduced;

[0067] (2) By setting the annular groove 2212 as a variable cross-section structure so that the cross-sectional area of ​​its lower end is larger than the cross-sectional area of ​​its upper end, the electromagnetic force required to be provided by the control valve 22 during operation can be reduced, thereby reducing the volume of the control valve 22, saving installation space, and providing more possibilities for the smart design of the injector.

[0068] The above contents are only preferred embodiments of the present invention. For ordinary technicians in this field, according to the concept of the present invention, there will be changes in the specific implementation methods and application scopes. The content of this specification should not be understood as limiting the present invention.

Claims

1. A fuel injector, characterized in that: It comprises a pressure boosting unit (1) and a fuel injection unit (2); The boosting part (1) comprises a boosting cylinder (11) and a piston (12), wherein the piston (12) is movably disposed in the inner cavity of the boosting cylinder (11), and two ends of the piston (12) respectively cooperate with two ends of the inner cavity of the boosting cylinder (11) to form a boosting oil inlet cavity (13) and a boosting oil outlet cavity (14); The fuel injection portion (2) comprises a fuel injector body (21), a control valve (22) and a needle valve (23); the fuel injector body (21) is provided with a fuel inlet (211), a fuel drain port (212) and a fuel injection port (213); along the axial direction of the fuel injector body (21), the control valve (22) and the needle valve (23) are sequentially installed in the fuel injector body (21); two ends of the needle valve (23) cooperate with the inner wall of the fuel injector body (21) to form a control chamber (214) and a fuel injection chamber (215); the fuel injection chamber (215) is formed on the fuel injector body (21). The oil injection port (213) is formed, the oil inlet (211) is connected to the boost oil inlet chamber (13), the boost oil outlet chamber (14) and the control chamber (214), the boost oil outlet chamber (14) is connected to the oil injection chamber (215), the control chamber (214) is connected to the oil drain port (212), and a first on-off port (216) is provided on the oil path connecting the control chamber (214) and the oil drain port (212), and a second on-off port (217) is provided on the oil path connecting the oil inlet (211) and the boost oil inlet chamber (13); The control valve (22) comprises a movable control valve stem (221) and a driving mechanism drivingly connected to the control valve stem (221), wherein the driving mechanism is configured to drive the control valve stem (221) to move to a first position, so that the control valve stem (221) simultaneously blocks the first on-off port (216) and the second on-off port (217), thereby causing the needle valve (23) to close the oil injection port (213); The driving mechanism is further configured to be capable of driving the control valve stem (221) to move to a second position, so that the control valve stem (221) simultaneously opens the first on-off port (216) and the second on-off port (217), thereby causing the needle valve (23) to open the oil injection port (213); A sealing valve ball (2211) is provided at the first end of the control valve stem (221), and an annular groove (2212) is provided on the circumferential outer wall of the second end of the control valve stem (221); When the control valve stem (221) is located at the first position, the sealing valve ball (2211) abuts against the first on-off opening (216) to block the first on-off opening (216), and the annular groove (2212) is connected to at most one of the oil inlet (211) and the boost oil inlet chamber (13) to block the second on-off opening (217); When the control valve stem (221) is located at the second position, the sealing valve ball (2211) is lifted away from the first on-off port (216) to open the first on-off port (216), and the annular groove (2212) is simultaneously connected to the oil inlet port (211) and the pressurized oil inlet chamber (13) to open the second on-off port (217); The control valve (22) is a solenoid valve, and along the direction from the second end of the control valve stem (221) to the first end of the control valve stem (221), the drive mechanism comprises a compression spring (222), a first return spring (223), an iron core coil assembly (224), and an armature (225) which are arranged in sequence; The compression spring (222) is arranged between the inner wall of the injector body (21) and the end surface of the second end of the control valve stem (221); the first return spring (223) is sleeved outside the control valve stem (221), and the two ends of the first return spring (223) are respectively fixedly connected to the control valve stem (221) and the injector body (21); the iron core coil assembly (224) is fixedly installed in the injector body (21); and the armature (225) is fixedly sleeved outside the control valve stem (221) and arranged opposite to the iron core coil assembly (224); When the iron core coil assembly (224) is not energized, the compression spring (222) and the first return spring (223) provide elastic force to keep the control valve stem (221) in the first position; when the iron core coil assembly (224) is energized, the iron core coil assembly (224) drives the control valve stem (221) to move from the first position to the second position via the armature (225).

2. The fuel injector according to claim 1, characterized in that: Along the direction from the second end of the control valve stem (221) to the first end of the control valve stem (221), the cross-sectional area of ​​the annular groove (2212) in a direction perpendicular to the axial direction of the control valve stem (221) gradually increases.

3. The fuel injector according to claim 1, characterized in that: The piston (12) is a T-shaped piston, the large end of the T-shaped piston is the first end of the piston (12), and the small end of the T-shaped piston is the second end of the piston (12).

4. The fuel injector according to claim 1, characterized in that: A one-way valve (24) is provided on the oil circuit connecting the oil inlet (211) and the pressurized oil outlet chamber (14); the inlet of the one-way valve (24) is connected to the oil inlet (211), and the outlet of the one-way valve (24) is connected to the pressurized oil outlet chamber (14).

5. The fuel injector according to claim 1, characterized in that: The needle valve (23) comprises a needle valve stem (231), wherein the needle valve stem (231) is configured to be able to move to a third position when the oil pressure in the control chamber (214) is greater than the oil pressure in the oil injection chamber (215) so as to block the oil injection port (213), and the needle valve stem (231) is also configured to be able to move to a fourth position when the oil pressure in the control chamber (214) is less than the oil pressure in the oil injection chamber (215) so as to open the oil injection port (213).

6. The fuel injector according to claim 5, characterized in that: Along the axial direction of the injector body (21), the control valve stem (221), the control chamber (214) and the needle valve stem (231) are arranged in sequence.

7. The fuel injector according to any one of claims 1 to 6, characterized in that: The boosting part (1) and the fuel injection part (2) are fixedly connected to form an integrated structure.

8. A common rail fuel injection system, characterized in that: Comprising the fuel injector according to any one of claims 1 to 7, the common rail fuel injection system further comprises a common rail pipe, the outlet of the common rail pipe is connected to the fuel inlet (211) of the fuel injector.

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